Charlene’s appearance comes days after her visit to a new exhibition in Pennsylvania with her husband Prince Albert. The display gives an insight into the life of Prince Albert’s mother, Princess Grace.

“Most of the world knows my mother first as a Hollywood film actress, then as the princess of Monaco,” said the prince in a video at the event.

“She was indeed a beautiful and talented woman and a fashion icon but that is just the surface of her life.

“Those of us who were fortunate enough to know my mother, her family and friends, knew her to be a genuine, warm and loving woman. A woman who always put her family first.

“I hope that through experiencing this exhibition, you will be able to get a glimpse of the real Grace Kelly, the woman beyond the icon, my mother.”